The
b
element represents a
span of text offset from its surrounding content without
conveying any extra emphasis or importance, and for which the
conventional typographic presentation is bold text; for
example, keywords in a document abstract, or product names in
a review.

Although previous versions of HTML defined the
b
element only in presentational terms, the element has now been
given the specific semantic purpose of representing text
“offset from its surrounding content without conveying any
extra emphasis or importance, and for which the conventional
typographic presentation is bold text”.